Drilling rigs often include a machine known as a draw works or hoist for raising and lowering piping and drill bits. A typical draw works includes a drill line wound around a large drum or spool. The drill line extends from the drum through a pulley or other block and tackle arrangement to a travelling block. A, drive system rotates the drum to reel in the drill line and a brake lever may be manually operated to apply or release one or more component of a brake assembly connected to the drum. For example, the brake lever may be positioned to manually release the brake assembly to allow the drive system to rotate the drum to reel in the drill line and raise the travelling block. Alternately, the drive system may be disconnected from the drum, and the brake lever may be positioned to manually release the brake assembly to allow the weight of the travelling block to rotate the drum to release drill line from the drum and lower the travelling block.
Unfortunately, conventional braking systems for draw works have many disadvantages. For example, the manually operated brake lever is often difficult to actuate or rotate (particularly with heavy loads), thereby increasing operator fatigue. In addition, the typical practice is to use a heavy chain to hold the brake lever in its engaged position when the operator leaves his/her station to ensure that the brake assembly remains engaged. However, if the chain is not properly installed, the brake lever may release, thereby disengaging the brake. Moreover, in some instances, the brake assembly and the drum flange may be extremely hot due to constant use of the brake. In such instances, as the brake assembly cools, one or more of the components of the brake assembly may contract and no longer maintain contact with the other brake assembly components, which may cause the brake to become disengaged. As is generally understood, given the heavy loads typically accommodated by a draw works, any unintentional release of the braking system has the potential to cause significant damage to the drilling rig (and/or its associated components) and/or injury to nearby personnel.
Accordingly, an improved braking system for a draw works used in connection with a drilling rig would be welcomed in the technology.